Suppression of thyroid-stimulating hormone (TSH) after thyroidectomy for low-risk cancer does not appear to reduce the risk of cancer recurrence and may even increase the risk of osteoporosis in women, according to the results of a study presented at the 83rd Annual Meeting of the American Thyroid Association, October 16- 20, 2013, in San Juan, Puerto Rico.
The thyroid is a gland in the throat that produces hormones mostly related to metabolic processes in the body. Nearly 95% of all thyroid cancers are classified as differentiated thyroid cancers; the distinction refers to the type and characteristics of the cancer cells.
TSH stimulates the proliferation of thyroid cells. Most patients who undergo thyroidectomy are treated with long-term suppression of TSH in order to inhibit growth; however, there is no evidence-based consensus on the optimal TSH level needed to reduce the risk of cancer recurrence, yet minimize adverse effects, such as hyperthyroidism.
Researchers conducted a retrospective study of 771 patients who were treated for thyroid cancer at Memorial Sloan Kettering Cancer Center between 2000 and 2006, and were followed for a median of 6.5 years. This was a composite of atrial fibrillation and osteoporosis. After excluding patients with high-risk cancer, primary hyperparathyroidism, atrial fibrillation or osteoporosis before surgery, they were left with 756 patients in the overall analysis. After excluding men, the osteoporosis analysis included 537 women.
TSH suppression was defined as a median level of 0.4 mU/L or less. The analysis indicated that there was no difference between those with suppressed TSH and those without in terms of disease-free survival. In fact, analysis confirmed that TSH suppression was not a predictor of recurrence.
However, TSH suppression was associated with a significantly increased risk of adverse events. Women with suppressed TSH levels were three times as likely to develop osteoporosis compared with those whose levels were not suppressed. Even after adjusting for age—a major factor in osteoporosis—TSH remained a strong predictor for the condition. The risk of osteoporosis appeared to taper with less TSH suppression, but risk of recurrence remained the same. TSH suppression was not linked with a significantly increased risk of atrial fibrillation.
The researchers concluded that TSH suppression does not provide recurrence benefits, but does increase the risk of osteoporosis—indicating that the risks of TSH suppression might outweigh the benefits.
Smith AW Wang LY, Palmer FL, et al. TSH suppression increases the risk of osteoporosis without changing recurrence in non-high risk patients with thyroid carcinoma. Presented at the 83rd Annual Meeting of the American Thyroid Association, October 16- 20, 2013, in San Juan, Puerto Rico. Thyroid. October 2013, 23(S1): A-115-A-121. Abstract 5.